Histochemical alterations in rabbit testis produced by manganese chloride

Abstract Early histochemical alterations in the testes of rabbits after daily iv administration of 3.5 mg/kg manganese chloride were studied. Manganese inhibited succinic dehydrogenase activity in seminiferous tubules after 5 days at a time when morphologic alterations were not apparent. This initial disturbance in energy synthesis resulted in slower cell metabolism leading to inhibition of glucose-6-phosphate dehydrogenase and NADH-diaphorase. Alkaline phosphatase activity in early stages of manganese toxicity did not appear to be affected. Initially, manganese seemed to affect germinal function of testicular tissue without disturbing steroidogenesis in that key enzymes in steroid biosynthesis, 3β-hydroxysteroid and glucose-6-phosphate dehydrogenases, in interstitial tissue were not affected in early stages of toxicity. An increase in the activity of these enzymes at later periods may be considered a consequence of tubular shrinkage with a relative increase in interstitial tissue. It was concluded that in the early stages of manganese toxicity, germinal function of the testes was affected by interference with energy synthesis in cells of the seminiferous tubules.